Children and adolescents meeting DSM-III-R criteria for schizophrenia are being obtained through vigorous national recruiting. Forty-five subjects and their families have participated to date in this study of the phenomenology, neurobiology and pharmacologic response of childhood onset schizophrenia. Over 1000 medical records have been reviewed from which 200 patients and their families appearing to meet DSM-III-R criteria for schizophrenia with onset of psychosis prior to age 12, were screened in person. A total of 55 received the diagnosis of schizophrenia at screening. A large number of children are receiving the diagnosis of schizophrenia inappropriately resulting in inappropriate treatment, even at major academic centers. Our findings to date indicate continuity between childhood onset and later onset schizophrenia, with evidence that childhood onset schizophrenia may result from a more severe neurodevelopment lesion. Pilot family/genetic data indicate three cases (10%) have familial schizophrenia, not higher than seen with NIMH adult cases; one subject had a 1:7 balanced chromosomal translocation; two subjects had a microdeletion at 22q11; one had 45x0 (Turners Syndrome). Three of 45 full siblings are mentally retarded. Probands show greater premorbid developmental delay particularly for language, than seen for the later onset disorder. Autonomic and eye tracking measures parallel these of adult schizophrenia. Brain MRI abnormalities resemble those of adult onset schizophrenia with the exception of more striking and consistent progression with age. A double-blind comparison of olanzapine and clozapine is ongoing. Several lines of evidence indicate greater genetic loading for these cases and our national case finding is being expanded to obtain 120 probands for future genetic studies. - Child and Adolescents, schizophrenia, chromosomal translocation, MRI, clozapine, genetics - Human Subjects & Human Subjects: Interview, Questionaires, or Surveys Only